The present invention relates to an antenna system for receiving and transmitting clockwise and counterclockwise circularly polarized wave signals.
Recently, many countries have been participating in satellite communication. Various kinds of antenna for receiving broadcast waves from satellites have been developed.
Satellite communication on 12 GHz band uses circularly polarized waves to avoid crosstalk between channels and between broadcast waves of various countries. Each of these countries are allocated a particular frequency band and either clockwise or counterclockwise circularly polarized waves. In addition, the positions of satellites in stationary orbits are also fixed for each country. In some cases, two or more satellites are positioned in one place to transmit clockwise and counterclockwise circularly polarized waves respectively.
In such a situation, if one satellite communication-receiving antenna system can receive clockwise and counterclockwise circular polarized waves simultaneously or at different times, it would be extremely useful because it can receive more broadcast waves than previously known satellite communication-receiving antenna systems.
In general, a satellite communication-receiving antenna system is composed of a reflector and a primary radiator fixed on the focus of the reflector. The primary radiator is usually designed and used for receiving either clockwise or counterclockwise circularly polarized waves.
To receive clockwise and counterclockwise circularly polarized waves sent from different broadcasting satellites by the conventional antenna system, therefore, the system must be equipped with a plurality of reflectors and primary radiators. As a result, the system construction cost and labor increase accordingly.
Therefore, an antenna system of simple construction capable of receiving both clockwise and counterclockwise circularly polarized waves, if realized, is quite useful for satellite communication.